Codesigning macOS apps with GNUstep-make

GNUstep-make adds a stamp file (for example, stamp.make) inside the .app bundle directory, for internal dependency tracking. The macOS codesign tool rejects bundles containing unexpected files, so the stamp file must be removed before you sign your app.

Use a GNUstep-make hook to remove the stamp file before signing, for example, in a before-install:: hook.